Added active objects, for editing.  Working on font texture manager and new label rendering.  Moving some of the builders out into their own modules so the active objects can use them.
Selection logic moved into its own manager so it can be called from more than one thread.  Added an explicit find object at location method.  Font texture manager now working, but more to do.
Messing with cache policy
Nearly finished with texture based fonts.  Moved font manager into the scene.